Field of the Invention
The present invention relates to a piezoelectric material, and in particular, to a lead-free piezoelectric material. The present invention also relates to a piezoelectric element, a multilayered piezoelectric element, a liquid ejection head, a liquid ejection apparatus, an ultrasonic motor, an optical apparatus, a vibration apparatus, a dust removing device, an image pickup device, and an electronic apparatus, all of which use the piezoelectric material.
Description of the Related Art
ABO3 perovskite-type metal oxides such as lead zirconate titanate (hereinafter referred to as “PZT”) are typically used as piezoelectric materials. However, since PZT contains lead as an A-site element, the effect of PZT on the environment has been regarded as a problem. Thus, piezoelectric materials that include lead-free perovskite-type metal oxides have been desired.
An example of a piezoelectric material that includes a lead-free perovskite-type metal oxide is barium titanate. In order to improve the properties of barium titanate, materials having a barium-titanate-based composition have been developed. Japanese Patent Laid-Open No. 2009-215111 discloses materials whose piezoelectric constants have been improved by adding Ca and Zr to barium titanate. However, these materials have phase transition temperatures at around room temperature, and thus the properties of these materials significantly vary depending on the environmental temperature. Thus, these materials are difficult to use in a wide temperature range. Furthermore, since these materials have a small mechanical quality factor, the materials may undergo depolarization when an alternating voltage is applied thereto.
Japanese Patent Laid-Open No. 2010-120835 discloses a material obtained by adding Ca and Cu to barium titanate. These materials have mechanical quality factors superior to that of barium titanate but have low piezoelectric properties.
The present invention provides a lead-free piezoelectric material that has a good, stable piezoelectric constant and a good, stable mechanical quality factor in a wide temperature range. Furthermore, the present invention provides a piezoelectric element, a multilayered piezoelectric element, a liquid ejection head, a liquid ejection apparatus, an ultrasonic motor, an optical apparatus, a vibration apparatus, a dust removing device, an image pickup device, and an electronic apparatus, all of which use the piezoelectric material.